1. Field of the Invention
The invention relates to automatic toilet bowl cleaners and to packages therefor, although the packages are useful for any incompatable solids, including other household cleaner applications.
2. Description of Related Art
Automatic toilet bowl cleaners have been used for many years to clean toilet bowls. The cleaners are usually purchased in the form of a solid puck or block and are placed in the cistern or resevoir of a toilet. As the solid dissolves over time, it releases various cleaning agents to the cistern. The cleaning agents are transferred to the toilet bowl upon flushing, and the fresh water introduced into the cistern dissolves additional cleaning agents from the solid.
Automatic toilet bowl cleaners typically fall into two well-defined formulations: (a) pucks or blocks that deliver halogen, acids or other bleaching agents and (b) pucks or blocks that deliver detergent materials, such as surfactants, and dyes or coloring agents that give an aesthetic color to the water in the toilet bowl. The halogen pucks usually comprise hydantoins that slowly chlorinate or brominate the surrounding water. Such pucks are described in, for example, U.S. Pat. No. 5,178,787 to Hung et al., issued Jan. 12, 1993. Detergent blocks usually comprise surfactant materials, a dye, typically a blue dye, and, optionally fragrance materials. Such blocks are described in, for example, U.S. Pat. No. 4,820,449 to Menke et al. issued Apr. 11, 1989.
For ease of reference herein, the former type of automatic toilet bowl cleaner shall be referred to as a bleach puck and the latter type as a detergent block. Persons skilled in the art will recognize that no limitation as to the shape of the cleaners should be inferred from these names. The cleaners may take any desired shape. Indeed, one commercial detergent "block" is offered for sale in the shape of a duck. Most products, however, are offered for sale in the form of a rounded puck or a rectilinear block.
Just as those skilled in the art will not infer a given shape from the names of the cleaners, neither will those skilled in the art draw any inference regarding the specific formulations contemplated by the names. Bleach pucks may comprise any agent for cleaning toilets or killing germs that will react with the dye, fragrance or any other agent present in a detergent block. While most commercial detergent blocks comprise surfactants and other mild cleaning agents that do not degrade the dye normally found in such products, it is possible to have a "detergent" block that does not have detergents. All that is required is that one ingredient, usually the active cleaning ingredient, of the bleach puck degrade at least one agent of the detergent block, such as a dye or fragrance, if the two solid forms are in physical contact.
Several attempts have been made to combine the two types of automatic toilet bowl cleaners. In one attempt, U.S. Pat. No. 4,460,490 to Barford et al., issued Jul. 17, 1984, the two types were simply joined together forcibly to be sold to the consumer as a single unit. One type of cleaning block is simply imbedded in or adhered to the other type of cleaning block. The patent acknowledges that the bleaching agent of the bleach tablet may discolor the dye in the detergent block. But, the patent suggests that this problem may simply be ignored. In the alternative, the patent suggests sandwiching a coating or liner of a water soluble or water dispersible material between the two intimately joined tablets. The manufacturing difficulties of attaching these two separate and incompatable materials are readily apparent.
Another attempt is shown in U.S. Pat. No. 4,568,207 to Holdt et al., issued Mar. 25, 1986, (Holdt I) and U.S. Pat. No. 4,683,072 to Holdt et al., issued Jul. 28, 1987, (Holdt II). In these patents, a single block or tablet has a single substrate containing a surfactant. Other ingredients are incorporated into separate regions of the single block or tablet. One region has a dye and a fragrance, while another region has either (a) a chlorine releasing agent or (b) a peroxide bleaching agent or an acid (Holdt I and Holdt II, respectively). The manufacturing difficulties inherent in making such a combination product are also apparent.
U.S. Pat. No. 4,597,941 to Bottom et al., issued Jul. 1, 1986, is another attempt to solve the problem by using a two-chambered dispenser as well as a bleach resistant dye. Unfortunately, the consumer must periodically either replace or "reload" the dispenser, which may prove to be inconvenient or unpleasant.
Thus there is still a strong need in the art for a combination product that is effective in use and that does not degrade due to chemical interaction during storage. The combination product must also be simple to manufacture and must be easy for the consumer to use. We have discovered that the solution to the problem lies both in the formulation used and in the packaging of the combination product.